1. Field of the Invention
The disclosure herein generally relates to a laminated glass and vehicle window.
2. Description of the Related Art
A laminated glass, in which two glass plates are laminated via an intermediate film, is provided with a resistance to penetration and a scattering prevention performance, and used for a window of building or a window of vehicle. Especially, a curved laminated glass is used for a vehicle, particularly a windshield, as a window that suppresses an aeromechanical resistance of the vehicle and a window having an aesthetic appearance.
In Recent years, weight saving of vehicles has been required against a background of increasing of fuel consumption of vehicles, proposal for hybrid vehicles or fuel cell vehicles, and the like. In the weight saving of a vehicle, in order to reduce weights of windows, there is a proposal for decreasing a plate thickness of a glass plate used for the laminated glass. Specifically, the proposal includes making the plate thickness of one of the glass plates configuring the laminated glass less than or equal to 1 mm. Furthermore, there is also a proposal for securing a prescribed strength by using a chemically strengthened glass for a glass plate having smaller plate thickness.
The laminated glass used for a vehicle window is typically curved. A curved laminated glass is generally manufactured as follows. Two uncurved glass plates are laminated and placed on a ring-shaped mold, and conveyed in a heating furnace, and thereby two curved glass plates with curvature radii that match with each other are prepared. In this case, because both glass plates are shaped without being rapidly cooled, the glass plates are not strengthened glass. When a chemically strengthened glass is used for the above-described glass plate having smaller plate thickness, the following trouble occurs. That is, when an uncurved chemically strengthened glass plate and another uncurved glass plate are laminated and placed on the ring-shaped mold, and conveyed in the heating furnace, a strengthening stress of the chemically strengthened glass is released by heating. As one considered approach in order to remove the above-described trouble, once the two curved glass plates are prepared, thereafter, one of the glass plates may be subjected to the chemically strengthened process. However, such management of a combination of the two glass plates shaped by the same ring-shaped mold is complicated and not practical.
Japanese Unexamined Patent Application Publication No. 2007-197288 discloses forcibly elastically deforming an uncurved glass plate having small plate thickness to follow a glass plate that has been curved and shaped in advance, and bonding by an intermediate layer or an adhesive layer lying between both glass plates.